Linear motion rolling guide unit having mounting arrangement adapted to eliminate track deformation

Abstract

A linear motion rolling guide unit that obtains high operating accuracy while suppressing sliding resistance to a low level without affecting the mounting state. The bottom surfaces of countersunk portions for insertion of fastening members are formed so as to be positioned, in the direction of said fastening, either on or below a hypothetical extended surface of that one of two bearing surfaces of a track surface that is positioned in said direction of fastening of the fastening member. The opening angle of the track surface is thus not narrowed by the fastening of said fastening members thus allowing high operating accuracy to be obtained and sliding resistance to be suppressed to a low level.

What is claimed is: 
     
       1. A linear motion rolling guide unit comprising: a first rack rail and a second track rail, said first track rail including a track surface having two intersecting bearing surfaces and a roughly V-shaped cross-section, said second track rail including a track surface formed into a projection, said V-shape and said projection being formed along a lengthwise direction, said projection being arranged so as to be inserted into said V-shape;   a plurality of cylindrical rollers arranged between said V-shape and said projection, and which roll over said bearing surfaces;   countersunk portions and insertion holes, which allow insertion of fastening members in a direction roughly perpendicular to a center line of an angle formed by said V-shape, and which are formed concentrically in at least said first track rail having said V-shape;   wherein, bottom surfaces of said countersunk portions are positioned either on or below a hypothetical extended surface of a lower one of the bearing surfaces.   
     
     
       2. The linear motion rolling guide unit of claim 1, wherein said first track rail has a mounting surface on its bottom for mounting to a prescribed frame, said track surface of said first track rail and countersunk portions being formed in the side and uppermost side, respectively, of said first track rail, and said direction is the direction from said uppermost portion towards said mounting surface.